We report on a concept inventory for special relativity: the development process,
data analysis methods, and results from an introductory relativity class.
Full abstract.

We report on a concept inventory for special relativity: the development process,
data analysis methods, and results from an introductory relativity class.
The Relativity Concept Inventory tests understanding of kinematic relativistic concepts.
An unusual feature is confidence testing for each question.
This can provide additional information; for example high confidence correlated with
incorrect answers suggests a misconception. A novel aspect of our data analysis is
the use of Monte Carlo simulations to determine the significance of correlations.
This approach is particularly useful for small sample sizes, such as ours.
Our results include a gender bias that was not present in other assessment,
similar to that reported for the Force Concept Inventory.

When interactions are turned off, the theory of interacting quantum and
classical ensembles due to Hall and Reginatto is shown to suffer from a
nonlocal signaling effect that is effectively action at a distance.
Full abstract.

When interactions are turned off, the theory of interacting quantum and
classical ensembles due to Hall and Reginatto is shown to suffer from a
nonlocal signaling effect that is effectively action at a distance. This limits
the possible applicability of the theory. In its present form, it is restricted
to those situations in which interactions are always on, such as classical
gravity interacting with quantized matter.

We report on the successful implementation of a development cycle for a physics teaching
package based on game-like virtual reality software.
Full abstract.

We report on the successful implementation of a development cycle for a physics teaching
package based on game-like virtual reality software. The cycle involved several
iterations of evaluating students' use of the package followed by instructional
and software development. The evaluation used a variety of techniques including
ethnographic observation, surveys, student focus groups and conventional assessment.
The teaching package included a laboratory manual, instructional support materials,
and the Real Time Relativity software that simulates a world obeying special relativistic physics.
Although the iterative development cycle was time consuming and costly,
it provided substantial improvements in the software user interface and in the
student's learning experience.

We apply Hall and Reginatto's theory of interacting classical and quantum ensembles to
harmonically coupled particles, with a view to understanding its experimental implications.
Full abstract.

We apply Hall and Reginatto's theory of interacting classical and quantum ensembles to
harmonically coupled particles, with a view to understanding its experimental implications.
This hybrid theory has no free parameters and makes distinctive predictions that should
allow it to be experimentally distinguished from quantum mechanics. It also bears on the
questions of quantum measurement and quantum gravity.

Causality in electrodynamics is a subject of some confusion, especially regarding the application
of Faraday's law and the Ampere-Maxwell law. This has led to the suggestion that we should not
teach students that electric and magnetic fields can cause each other, but rather focus on
charges and currents as the causal agents. In this paper I argue that fields have equal
status as casual agents, and that we should teach this.
Full abstract.

Causality in electrodynamics is a subject of some confusion, especially regarding the application
of Faraday's law and the Ampere-Maxwell law. This has led to the suggestion that we should not
teach students that electric and magnetic fields can cause each other, but rather focus on
charges and currents as the causal agents. In this paper I argue that fields have equal
status as casual agents, and that we should teach this. Following a discussion of causality
in classical physics I will use a numerical solution of Maxwell's equations to inform a
field based causal explanation in electrodynamics.

Collapsing Bose-Einstein condensates are rich and complex quantum systems for
which quantitative explanation by simple models has proved elusive.
We present new experimental data on the collapse of high density Rb-85 condensates
with attractive interactions and find quantitative agreement with the predictions
of the Gross-Pitaevskii equation.
Full abstract.

Collapsing Bose-Einstein condensates are rich and complex quantum systems for
which quantitative explanation by simple models has proved elusive.
We present new experimental data on the collapse of high density Rb-85 condensates
with attractive interactions and find quantitative agreement with the predictions
of the Gross-Pitaevskii equation. The collapse data and measurements of the decay
of atoms from our condensates allow us to put new limits on the value of the Rb-85
three-body loss coefficient K_3 at small positive and negative scattering lengths.

Amongst the great changes in society is the use of simulations for activities as diverse as public policy
making and recreation. These simulations are routinely coupled to sophisticated visual interfaces
producing virtual realities. This project has produced examples of how recent developments in
simulation technology may be used for learning and teaching physics.
Full abstract.

Amongst the great changes in society is the use of simulations for activities as diverse as public policy
making and recreation. These simulations are routinely coupled to sophisticated visual interfaces
producing virtual realities. This project has produced examples of how recent developments in
simulation technology may be used for learning and teaching physics.

In computer games users must learn to understand and manipulate unfamiliar worlds.
But much of physics deals with unfamiliar domains: such as the very fast or the very small.
The physics of these domains, relativity and quantum mechanics, is abstract and counter-intuitive.
We have found that simulations of these domains can help students learn the physics.
The visual learning they enable complements more abstract forms of instruction.

Computer simulations have been used for a long time in physics teaching.
They open up complex and realistic scenarios to students and instructors alike.
They also allow access to processes which are difficult, or impossible, to observe in the lab.
What is new about our approach is the emphasis on immersive, interactive, first-person, game-like simulation.
This facilitates student-led discovery learning and gives students another pathway into the physics.

We present an investigation of game-like simulations for physics teaching. We report on the effectiveness of
the interactive simulation "Real Time Relativity" for learning special relativity. We argue that the simulation not only
enhances traditional learning, but also enables new types of learning that challenge the traditional curriculum.
Full abstract.

We present an investigation of game-like simulations for physics teaching. We report on the effectiveness of
the interactive simulation "Real Time Relativity" for learning special relativity. We argue that the simulation not only
enhances traditional learning, but also enables new types of learning that challenge the traditional curriculum. The
lessons drawn from this work are being applied to the development of a simulation for enhancing the learning of
quantum mechanics.

We present a study of student learning through the use of virtual reality. A software package
is used to introduce concepts of special relativity to students in a game-like environment where
users experience the eﬀects of travelling at near light speeds. From this new perspective, space
and time are signiﬁcantly diﬀerent to that experienced in everyday life. The study explores how
students have worked with this environment and how these students have used this experience in
their study of special relativity.
Full abstract.

We present a study of student learning through the use of virtual reality. A software package
is used to introduce concepts of special relativity to students in a game-like environment where
users experience the eﬀects of travelling at near light speeds. From this new perspective, space
and time are signiﬁcantly diﬀerent to that experienced in everyday life. The study explores how
students have worked with this environment and how these students have used this experience in
their study of special relativity. A mixed method approach has been taken to evaluate the outcomes
of separate implementations of the package at two universities. Students found the simulation to
be a positive learning experience and described the sub ject area as being less abstract after its
use. Also, students were more capable of correctly answering concept questions relating to special
relativity, and a small but measurable improvement was observed in the ﬁnal exam.

Mastery learning in a large first year physics class,
P. Francis, C. Figl. C. Savage, Proceedings of the UniServe Science Symposium on Motivating Science Undergraduates: Ideas and Interventions, October 2009.Proceedings

In 2009 we tried an experiment in our large core first year physics course: we introduced mastery learning.
The basic idea behind mastery learning is that any student can learn anything well, but that it takes some students much
longer than others. We should therefore let students proceed through a course at different speeds, while insisting that
they totally master each section of the course before moving on.
Full abstract.

In 2009 we tried an experiment in our large core first year physics course: we introduced mastery learning.
The basic idea behind mastery learning is that any student can learn anything well, but that it takes some students much
longer than others. We should therefore let students proceed through a course at different speeds, while insisting that
they totally master each section of the course before moving on.

The students have to get over 80% in each homework assignment before they are allowed to take the next one. They
are, however, allowed to take different versions of each assignment multiple times until they reach this threshold. At the
end, the weaker students would have covered less content than the strong ones, but they should have fully understood
whatever they did. In the laboratory component, the students were assessed in each experiment against a set of lab
mastery goals. The students could pass the lab component only if they have mastered each of these goals at least once.

Did it work? Logistically it worked very well, somewhat to our surprise. There were a number of striking unexpected
benefits: students did more work, complained less about the workload, asked for help more often, and showed an
improved ability to solve questions first time around. Gains in student conceptual understanding were much improved,
but this may be due to other innovations introduced in the course. Examination performance, however, did not improve,
even on the most basic material. Students could do the problems when given unlimited time and assistance from peers,
but not in exam conditions.

Ultra-cold clouds of dimeric molecules can dissociate into quantum
mechanically correlated constituent atoms that are either bosons or fermions.
We theoretically model the dissociation of cigar shaped molecular condensates,
for which this difference manifests as complementary geometric structures of
the dissociated atoms.
Full abstract.

Ultra-cold clouds of dimeric molecules can dissociate into quantum
mechanically correlated constituent atoms that are either bosons or fermions.
We theoretically model the dissociation of cigar shaped molecular condensates,
for which this difference manifests as complementary geometric structures of
the dissociated atoms. For atomic bosons beams form along the long axis of the
molecular condensate. For atomic fermions beams form along the short axis. This
directional beaming simplifies the measurement of correlations between the
atoms through relative number squeezing.

Learning Special Relativity is a highly anticipated experience for first year students; however, the
teaching and learning of Special Relativity are difficult tasks.
Full abstract.

Learning Special Relativity is a highly anticipated experience for first year students; however, the
teaching and learning of Special Relativity are difficult tasks. Special Relativity, while fundamentally and mathematically simple; has apparently bizarre implications and deals predominately with situations outside everyday experience. Understanding relativity requires one to accept that there is less that is absolute than was once believed and to accept a model of time and space that is strange and unfamiliar. As such, modifying everyday concepts of motion, time and space to
develop accurate constructs of the theory of Special Relativity is extraordinarily difficult. While Special Relativity is often featured in introductory physics courses, Scherr (2001) indicates many students fail to develop fundamental concepts in Special Relativity even after advanced instruction. To address these issues there has broad variety of efforts to determine the conceptual misunderstandings and develop activities to address them.

Real Time Relativity (RTR) is a virtual reality simulation of Special Relativity. Giving learners real
time control of how they explore and test the optical, spatial and time effects of near-light-speed
motion in a realistic environment enables a constructivist approach, previously unavailable, for
learning Special Relativity.

Given the hands-on nature of RTR, it has been incorporated into the experimental laboratories of
first year physics courses at the University of Queensland and the Australian National
University. These experiments enable students to explore relativistic effects without requiring
a detailed understanding of the theoretical framework. RTR experiments have been developed with an
active learning approach in which students learn by
developing, testing and refining their constructs with their peers. The RTR system and experiments
are currently being refined in a model inspired by the Physics Education Technology group at the
University of Colorado and
evaluated through a multimethods research approach. This
paper outlines our current point in a continuing development and evaluation project.

We perform a theoretical analysis of atomic four-wave mixing via a collision of two Bose-Einstein condensates of metastable helium atoms, and compare the results to a recent experiment.
Full abstract.

We perform a theoretical analysis of atomic four-wave mixing via a collision of two Bose-Einstein condensates of metastable helium atoms, and compare the results to a recent experiment. We calculate atom-atom pair correlations within the scattering halo produced spontaneously during the collision. We also examine the expected relative number squeezing of atoms on the sphere. The analysis includes first-principles quantum simulations using the positive P-representation method. We develop a unified description of the experimental and simulation results.

We analyze the dynamics of quantum statistics in a harmonically trapped Bose-Einstein condensate, whose two-body interaction strength is controlled via a Feshbach resonance. From an initially non-interacting coherent state, the quantum field undergoes Kerr squeezing, which can be qualitatively described with a single mode model.
Full abstract.

We analyze the dynamics of quantum statistics in a harmonically trapped Bose-Einstein condensate, whose two-body interaction strength is controlled via a Feshbach resonance. From an initially non-interacting coherent state, the quantum field undergoes Kerr squeezing, which can be qualitatively described with a single mode model. To render the effect experimentally accessible, we propose a homodyne scheme, based on two hyperfine components, which converts the quadrature squeezing into number squeezing. The scheme is numerically demonstrated using a two-component Hartree-Fock-Bogoliubov formalism.

We perform first-principles quantum simulations of dissociation of trapped, spatially inhomogeneous Bose-Einstein condensates of molecular dimers using the positive-P representation method. Specifically, we study spatial pair correlations of atoms produced in dissociation and analyze different correlation measures after time of flight.
Full abstract.

We perform first-principles quantum simulations of dissociation of trapped, spatially inhomogeneous Bose-Einstein condensates of molecular dimers using the positive-P representation method. Specifically, we study spatial pair correlations of atoms produced in dissociation and analyze different correlation measures after time of flight. These include Glauber's density-density correlation and number-difference squeezing in spatial column densities which correspond to the experimental method of shot noise spectroscopy in absorption images. We find that the strength of the observable correlations may significantly degrade in systems with strong spatial inhomogeneity compared to the predictions of idealized uniform models. We show how binning of the signal can enhance the detectable correlations and lead to the violation of the classical Cauchy-Schwartz inequality.

Quasi-one dimensional outflow from a dilute gas Bose-Einstein condensate reservoir is a promising
system for the creation of analogue Hawking radiation. We use numerical modeling to show that
stable sonic horizons exist in such a system under realistic conditions, taking into account the
transverse dimensions and three-body loss.
Full abstract.

Quasi-one dimensional outflow from a dilute gas Bose-Einstein condensate reservoir is a promising
system for the creation of analogue Hawking radiation. We use numerical modeling to show that
stable sonic horizons exist in such a system under realistic conditions, taking into account the
transverse dimensions and three-body loss. We find that loss limits the achievable analogue Hawking
temperatures, with sodium condensates allowing the highest temperatures. A condensate of 30,000
atoms, with transverse confinement frequency of 6800 × 2pi Hz, yields horizon temperatures
of about 20 nK over a period of 50 ms. This is at least four times higher than for other atoms
commonly used for Bose-Einstein condensates.

Real Time Relativity is a computer program that lets students fly at relativistic speeds though a simulated world populated with planets, clocks, and buildings. The counterintuitive and spectacular optical effects of relativity are prominent, while systematic exploration of the simulation allows the user to discover relativistic effects such as length contraction and the relativity of simultaneity.
Full abstract.

Real Time Relativity is a computer program that lets students fly at relativistic speeds though a simulated world populated with planets, clocks, and buildings. The counterintuitive and spectacular optical effects of relativity are prominent, while systematic exploration of the simulation allows the user to discover relativistic effects such as length contraction and the relativity of simultaneity. We report on the physics and technology underpinning the simulation, and our experience using it for teaching special relativity to first year university students.

We perform the first numerical three-dimensional studies of quantum field effects in the Bosenova experiment on collapsing condensates by E. Donley et al. [Nature 415, 39 (2002)] using the exact experimental geometry.
Full abstract.

We perform the first numerical three-dimensional studies of quantum field effects in the Bosenova experiment on collapsing condensates by E. Donley et al. [Nature 415, 39 (2002)] using the exact experimental geometry. In a stochastic truncated Wigner simulation of the collapse, the collapse times are larger than the experimentally measured values. We find that a finite temperature initial state leads to an increased creation of uncondensed atoms, but not to a reduction of the collapse time. A comparison of the time-dependent Hartree-Fock-Bogoliubov and Wigner methods for the more tractable spherical trap shows excellent agreement between the uncondensed populations. We conclude that the discrepancy between the experimental and theoretical values of the collapse time cannot be explained by quantum fluctuations or finite temperature effects.

Real Time Relativity is a computer program that allows the user to fly through a virtual world governed by relativistic physics.
Full abstract.

Real Time Relativity is a computer program that allows the user to fly through a virtual world governed by relativistic physics. The user controls a 'rocket' carrying a 'camera'. The rocket may be accelerated and steered, and the camera may be pointed in any direction. It takes advantage of the fact that video cards provide inexpensive data-parallel processing and are designed to perform rapid arithmetic on four-dimensional vectors.

We investigate the quantum many-body dynamics of dissociation of a
Bose-Einstein condensate of molecular dimers into pairs of constituent bosonic
atoms and analyze the resulting atom-atom correlations.
Full abstract.

We investigate the quantum many-body dynamics of dissociation of a
Bose-Einstein condensate of molecular dimers into pairs of constituent bosonic
atoms and analyze the resulting atom-atom correlations. The quantum fields of
both the molecules and atoms are simulated from first principles in three
dimensions using the positive-P representation method. This allows us to
provide an exact treatment of the molecular field depletion and s-wave
scattering interactions between the particles, as well as to extend the
analysis to nonuniform systems. In the simplest uniform case, we find that the
major source of atom-atom decorrelation is atom-atom recombination which
produces molecules outside the initially occupied condensate mode. The unwanted
molecules are formed from dissociated atom pairs with non-opposite momenta. The
net effect of this process -- which becomes increasingly significant for
dissociation durations corresponding to more than about 40% conversion -- is to
reduce the atom-atom correlations. In addition, for nonuniform systems we find
that mode-mixing due to inhomogeneity can result in further degradation of the
correlation signal. We characterize the correlation strength via the degree of
squeezing of particle number-difference fluctuations in a certain
momentum-space volume and show that the correlation strength can be increased
if the signals are binned into larger counting volumes.

We have developed a relativistically-accurate computer graphics code and have used it to produce photo-realistic images and videos of scenes where special relativistic effects dominate, either in astrophysical contexts or in imaginary worlds where the speed of light is only a few metres per second.
Full abstract.

We have developed a relativistically-accurate computer graphics code and have used it to produce photo-realistic images and videos of scenes where special relativistic effects dominate, either in astrophysical contexts or in imaginary worlds where the speed of light is only a few metres per second. The videos have been integrated into our under-graduate teaching programme for several years. Recently we took the next step, encouraging undergraduate students to use the code to explore relativity, develop their own videos, and eventually package them together into Through Einstein's Eyes, a multimedia CD.

We show that the stability of three-dimensional Skyrmions in trapped Bose-Einstein condensates depends critically on scattering lengths, atom numbers, trap rotation and trap anisotropy.
Full abstract.

We show that the stability of three-dimensional Skyrmions in trapped Bose-Einstein condensates depends critically on scattering lengths, atom numbers, trap rotation and trap anisotropy. In particular, for the 87Rb |F=1,mf=-1>, |F=2,mf=1> hyperfine states stability is sensitive to the scattering lengths at the level of their present experimental uncertainties. In a cigar shaped trap, we find stable Skyrmions with as few as 2 x106 atoms, a number which scales with the inverse square root of the trap frequency. These can be stabilized against drift out of the trap by laser pinning.

We show that sound waves scattered from a hydrodynamic vortex may be amplified. Such superradiant scattering follows from the physical analogy between spinning black holes and hydrodynamic vortices.
Full abstract.

We show that sound waves scattered from a hydrodynamic vortex may be amplified. Such superradiant scattering follows from the physical analogy between spinning black holes and hydrodynamic vortices. However a sonic horizon analogous to the black hole event horizon does not exist unless the vortex possesses a central drain, which is challenging to produce experimentally. In the astrophysical domain, superradiance can occur even in the absence of an event horizon: we show that in the hydrodynamic analogue, a drain is not required and a vortex scatters sound superradiantly. Possible experimental realization in dilute gas Bose-Einstein condensates is discussed.

We analyse quantum field models of the bosenova experiment, in which 85Rb Bose-Einstein condensates were made to collapse by switching their atomic interactions from repulsive to attractive.
Full abstract.

We analyse quantum field models of the bosenova experiment, in which 85Rb Bose-Einstein condensates were made to collapse by switching their atomic interactions from repulsive to attractive. Specifically, we couple the lowest order quantum field correlation functions to the Gross-Pitaevskii function, and solve the resulting dynamical system numerically. Comparing the computed collapse times with the experimental measurements, we find that the calculated times are much larger than the measured values. The addition of quantum field corrections does not noticeably improve the agreement compared to a pure Gross-Pitaevskii theory.

By direct comparison between experiment and theory, we show how the classical noise on a multi-state atom laser beam increases with increasing flux.
Full abstract.

By direct comparison between experiment and theory, we show how the classical noise on a multi-state atom laser beam increases with increasing flux. The trade off between classical noise and flux is an important consideration in precision interferometric measurement. We use periodic 10 microsecond radio-frequency pulses to couple atoms out of an F=2 87Rb Bose-Einstein condensate. The resulting atom laser beam has suprising structure which is explained using three dimensional simulations of the five state Gross-Pitaevskii equations.